netdev - Re: [PATCH net] net: sched: fix NULL pointer dereference when action calls some targets

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Date:   Thu, 17 Aug 2017 12:02:20 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     Xin Long <lucien.xin@...il.com>
Cc:     Cong Wang <xiyou.wangcong@...il.com>,
        network dev <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        netfilter-devel@...r.kernel.org,
        Jamal Hadi Salim <jhs@...atatu.com>
Subject: Re: [PATCH net] net: sched: fix NULL pointer dereference when action
 calls some targets

On Wed, Aug 16, 2017 at 08:39:44PM +1200, Xin Long wrote:
> On Wed, Aug 9, 2017 at 7:33 AM, Cong Wang <xiyou.wangcong@...il.com> wrote:
> > On Mon, Aug 7, 2017 at 7:33 PM, Xin Long <lucien.xin@...il.com> wrote:
> >> On Tue, Aug 8, 2017 at 9:15 AM, Cong Wang <xiyou.wangcong@...il.com> wrote:
> >>> This looks like a completely API burden?
> >> netfilter xt targets are not really compatible with netsched action.
> >> I've got to say, the patch is just a way to make checkentry return
> >> false and avoid panic. like [1] said
> >
> > I don't doubt you fix a crash, I am thinking if we can
> > "fix" the API instead of fixing the caller.
> Hi, Cong,
> 
> For now, I don't think it's possible to change APIs or  some of their targets
> for the panic caused by action xt calling.
> 
> The common way should be fixed in net_sched side.
> 
> Given that the issue is very easy to triggered,
> let's wait for netfilter's replies for another few days,
> otherwise I will repost the fix, agree ?

Please, post the workaround so the kernel doesn't crash anymore.

This is going to be very hard to fix, it's broken since the very
beginning...

Thanks!